For example, she said, when Danish newspapers published caricatures of the Prophet Muhammad, many Turks felt Muslims were obligated to kill the cartoonists because tradition held that the Prophet Muhammad ordered the execution of a poet.

But Ms. Somaz was surprised to learn some traditional scholars say the poet in Muhammad’s day was killed because he persecuted the nascent Muslim community and posed an existential threat.

“People think I do this just to enlighten non-Muslims, but actually my hidden goal is to enlighten Muslim youth and strengthen their faith,” Imam Solimon said. “If you tell them come to a workshop to strengthen your faith, they will not come. But if you tell them to come to a workshop and learn how to talk about Islam to non-Muslims, they come.”

While Imam Solimon is a reformer, he is far from liberal. Homosexuals can be Muslims, he said, but to actually act on their desires by committing sodomy is a sin. Stoning and amputation are valid punishments under Shariah, or Islamic law, he added, but for most of Islamic history, they were never applied because rulers and scholars understood the judicial system to be flawed, and the risk of punishing innocents was too great.

In 2010, Imam Solimon rebutted former al-Qaida spokesman Anwar al-Awlaki, whom he knew from their time in the U.S. together. Mr. Awlaki, a Yemeni-American, was a senior recruiter for al-Qaida and had issued a video calling for Muslims to kill all Americans, anywhere.

H.A. Hellyer, a nonresident senior fellow at the Atlantic Council and an associate fellow at the Royal United Services Institute, said that more than a reformation, the faith needs a revival of past scholarship.

“The (previous) ‘reformations’ that took place were more like the birth of the Salafi movement in the 18th century, which was not exactly very positive or progressive,” Mr. Hellyer said. “Indeed, it resulted in opening a ‘Pandora’s box’ that led to many perverted interpretations of religion in the Muslim world later on.”

He said that any meaningful change in Islamic thinking will require more scholars like Imam Solimon, who are willing to reach further back, before movements like the Salafi “reformation,” which taught Muslims to disregard centuries of scholarship considered flawed.

The aloofness to traditional Islamic scholarship helps extremist groups recruit, said David H. Schanzer, an adviser to the U.S. government on counterterrorism policy and an associate professor at Duke University. Extremists, he said, “aren’t well-versed in Islamic theology or jurisprudence.”

He gives the example of a Danish convert who confronted him at a 2005 lecture about why 9/11 was not justified in Islam.

Years later, Imam Solimon learned the man was Murad Storm, a former extremist who abandoned Islam and then helped U.S. and European intelligence agencies track down Mr. Awlaki in Yemen, where the cleric was killed by a drone strike.

“When people like (Mr. Storm) hear criticism of Islam for the first time, they are not able to handle it,” said Imam Solimon. “They become violent and try to defend what they think is Islam. (Eventually) they actually leave Islam.”